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A 30-year-old woman with Li-Fraumeni syndrome is found to have adenocarcinoma of the breast. Her family history includes osteosarcoma. Which of the following mechanisms most likely underlies this condition?

A
)
Activated proto-oncogenes

B
)
Defective detoxification enzymes

C
)
Defective DNA repair enzymes

D
)
Impaired regulation of apoptosis

E
)
Impaired signal transduction

I think d. P53 stimulates apoptosis. U can see it with osteosarcoma and retinoblastoma

p53 prevents cells with damaged or mutant DNA from progressing into S phase from G1 and making sure DNA repairs are done which will of course involve enzymes before S phase. So I would choose C. P53 mutation is responsible for Li-Fraumeni. I hope this helps.

i choose c i got it wrong.the ans is d

p53 prevents BCL-2. so cytochrome C leaks out and causes apoptosis. if p53 is mutated bcl will prevent cyt c from leaking and there will be no apoptosis

thanks a lot